Olfactory dysfunction in fragile X tremor ataxia syndrome

Area of Science:

• Neuroscience
• Genetics
• Olfactory Research

Background:

• Fragile X-associated tremor/ataxia syndrome (FXTAS) shares clinical features with other neurodegenerative disorders.
• Olfactory dysfunction is a known feature in several neurodegenerative conditions.

Purpose of the Study:

• To investigate olfactory identification capacity in individuals with FMR1 premutation, the genetic basis of FXTAS.
• To compare olfactory function between FMR1 premutation carriers and controls.

Main Methods:

• Olfactory identification was assessed using the University of Pennsylvania Smell Identification Test (UPSIT).
• Neurologic and cognitive evaluations were performed on 41 FMR1 premutation carriers and 42 controls.
• Motor function and cognitive status were measured using standardized rating scales.

Main Results:

• A significantly higher frequency of olfactory defects was observed in FMR1 premutation carriers (61%) compared to controls (29%).
• Olfactory defects were more frequent and severe in carriers with cognitive impairment.
• No correlation was found between olfactory scores and motor impairment severity.

Conclusions:

• FMR1 premutation carriers exhibit a heightened susceptibility to olfactory identification deficits.
• The prevalence and severity of olfactory dysfunction in carriers suggest a shared vulnerability across neurodegenerative diseases.
• These olfactory deficits correlate with cognitive status but are also present in cognitively intact carriers, warranting further investigation.